Process the cheese, flour, cornstarch, and salt together in a food processor (or blender) until combined. Add butter 1 piece at a time and process until mixture resembles wet sand, about 30 seconds. Add water and pulse until dough forms large clumps.

Transfer dough to a lightly floured surface. Divide in half and pat each into a square using your hands. This will just make it easier to roll out once it’s cold and hard. If the dough feels dry, moisten your fingers with cold water. Wrap each in parchment & refrigerate until firm, about 45 minutes & up to 2 days.

Preheat oven to 350°F. Line 2 large baking sheets with parchment paper or silicone baking mats.

On a lightly floured surface, roll out each dough square directly on your parchment or silicone mat. Add a tiny bit of flour on top if needed so it doesn’t stick to the rolling pin, but no need to flour your parchment/silicone mat. Trim edges and slice 1x1 inch squares. No need to separate the crackers as they will easily break apart after baking.

Use a skewer or chopstick to poke a hole through the center of each. Lightly sprinkle with sea salt. Bake until golden brown around the edges, about 16-18 minutes, rotating the baking sheets halfway through baking. For crunchier crackers, bake for 20 minutes. Note that they will continue to harden/crisp up as they cool down after baking. Be careful not to overcook them, as they can burn/overcook very easily. Unless you like them “extra toasty” which is delicious too.